Folding crane

ABSTRACT

A folding crane has a first boom comprising laterally spaced boom elements pivotally supported on a base, and a second boom pivoted in the space between said elements. The second boom swings between an extended position, and a folded position in which the swinging end of the second boom lies adjacent the pivotal support for the first boom, and between laterally spaced supports on the base which pivotally carry the first boom elements. Separate power means move each boom. The second boom is movable by gravity toward or away from folded position by changing the inclination of the first boom in order to cause the power means for the second boom to move through a dead-center position. In a modification, the power means for the second boom comprises an hydraulic cylinder having two pistons and piston rods, one piston rod projecting from each end of the cylinder. A barrier wall fixed within the cylinder isolates the hydraulic fluid acting on one piston with respect to the hydraulic fluid acting on the other piston.

nite States atent [1 1 Suverkrop [451 Aug. 28, 1973 Related US. Application Data [63] Continuation-impart of Ser. No. 17,390, March 9,

1970, Pat. No. 3,608,952.

109,530 1/1968 Denmark 212/35 308,381 2/1969 Sweden 175,997 7/ 1961 Sweden 212/46 Primary ExaminerEvon C. Blunk Assistant Examiner-Merle F. Mafi'ei Attorney-Lyon & Lyon [57] ABSTRACT A folding crane has a first boom comprising laterally spaced boom elements pivotally supported on a base, and a second boom pivoted in the space between said elements. The second boom swings between an extended position, and a folded position in which the swinging end of the second boom lies adjacent the pivotal support for the first boom, and between laterally spaced supports on the base which pivotally carry the first boom elements. Separate power means move each boom. The second boom is movable by gravity toward or away from folded position by changing the inclination of the first boom in order to cause the power means for the second boom to move through a deadcenter position. In a modification, the power means for the second boom comprises an hydraulic cylinder having two pistons and piston rods, one piston rod projecting from each end of the cylinder. A barrier wall fixed within the cylinder isolates the hydraulic fluid acting on one piston with respect to the hydraulic fluid acting on the other piston.

3 Claims, 7 Drawing Figures [52] US. Cl 212/59 R, 91/167, 212/46 A, 212/55 [51] Int. Cl. 1166c 23/06 [58] Field of Search 212/8, 35, 55, 59, 212/46, 46 A, 46 B, 144; 91/167 [56] References Cited UNITED STATES PATENTS 3,187,637 6/1965 Edmund 91/167 3,037,641 6/1962 Potter 212/46 A 3,244,292 4/1966 Elliott 212/59 3,543,944 12/1970 Woodside 212/55 FOREIGN PATENTS OR APPLICATIONS 978,765 12/1964 Great Britain 212/35 1,027,451 4/1966 Great Britain.... 212/59 301,038 5/1968 Sweden 212/35 660,906 4/1963 Canada 212/55 64,854 12/1968 Germany 212/55 890,736 3/1962 Great Britain 212/8 Patented Aug. 28, 1973 3 Sheets-Sheet 2 INVENTOR 00M SUI 625,60,

FOLDING CRANE This application is a continuation-in-part of my copending application Ser. No. l7,390 filed Mar. 9, 1970 now US Pat. No. 3,608,952.

This invention relates to folding cranes and is particularly directed to a device of this type adapted to be mounted on a mobile platform, for example a bed of a truck for highway travel. Present cranes now in use employ a single boom, and such cranes in larger sizes become unwieldy for highway transportation.

In accordance with the present invention, a first boom is mounted on a base for pivotal movement in a vertical plane, and a second boom is pivotally mounted near the swinging end of the first boom. The second boom may be swung to a folded position in which its outer swinging end is positioned near the pivotal support for the first boom, thereby reducing the overall length by about one-half for convenient highway travel.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIG. I is a side elevation showing a preferred embodiment of this invention, the parts being shown in folded position.

FIG. 2 is a side elevation showing the first boom in elevated inclined position, and the second boom hanging by gravity therefrom.

FIG. 3 is a side elevation showing the second boom in extended position.

FIG. 4 is a plan view showing the two booms in folded position.

FIG. 5 is a side elevation partly broken away, showing construction of the second boom.

FIG. 6 is a transverse cross-section taken substantially on the line 6--6 as shown in FIG. 5.

FIG. 7 is a sectional side elevation showing a modification.

Referring to the drawings, the truck generally designated 10 has the usual wheel-supported frame 11. A sub-base 12 is secured to the truck frame 11. This in turn supports a base 13 which can be turned around a vertical axis, 'in the usual fashion. I-Iydraulicallyoperated outriggers 14 are mounted on the sub-base l2.

In accordance with this invention, a first boom member 15 comprises a pair of laterally-shaped boom elements 16 connected by pivot pins 17 to laterally spaced supports 21 on the base 13. A second boom member 18 has a portion thereof received in the space 19 between the boom elements 16 and is pivotally connected to the boom elements 16 by means of the pivot pin 20.

Power means are provided for swinging the first boom 15 with respect to one of the base supports 21 in a vertical plane, and as shown in the drawings this power means includes a pair of hydraulic cylinder assemblies 22. One end of each assembly 22 is pivoted at 23 to the base 13, and the other end is pivoted to one of the boom elements 16 at 24. The hydraulic cylinder assemblies 22 move in unison to swing the first boom member 15 about the pivotal connections 17.

Second power means in the form of a hydraulic cylinder assembly 26 is provided for swinging the second boom member 18 around its pivot pin 20, in the same plane as the first boom member. One end of the assembly 26 is positioned in the space 19 between the boom elements 16 and is connected by pivot pin 27 to said boom elements. The other end of the assembly 26 is connected by pivot pin 28 to an element of the second boom member 18.

As shown in FIG. 1, the boom members 15 and 18 may be folded and lowered into position over the cab 29 of the truck 10 and rested on a stationary support 30 for travel over the highway. In this folded position, the swinging end 31 of the second boom member 18 is positioned closely adjacent the pivotal supports 17 for the first boom member 15, between the supports 21, and a portion of the second boom member 18 is positioned within the space 19 between the boom elements When the truck reaches the location where the crane is to be used, the hydraulic outriggers 14 are moved from the retracted position shown in FIG. I to the extended position shown in FIGS. 2 and 3. The hydraulic cylinder assemblies 22 are then energized to lift the first boom member 15 upward away from the truck cab 29, and the hydraulic cylinder assembly 26 is pressurized to hold the second boom member 18 in close proximity to the first boom member 15. It will be observed that, in the folded position shown in FIG. 1, the pivot pin 28 is positioned above the line L adjoining the axes of the pivot pins 20 and 27. Pressurizing of the cylinder assembly 26 therefore prevents the second boom member 18 from falling away from the first boom member 15 as the latter is lifted. When the boom members 15 and 18 have been lifted away from the cab 29 for a short distance, the base 13 is rotated approximately one-half revolution to bring the boom members away from the truck cab 29. The first boom 'member l5-is then raised to the inclined elevated position shown in FIG. 2, and the pressure in the hydraulic cylinder assembly 26 is relaxed. The second boom member 18 then swings by gravity down through the vertical position shown in FIG. 2, and this movement brings the pivot pin 28 to the other side of the line L. Accordingly, pressurizing of the hydraulic cylinder assembly 26 then serves to swing the second boom member 18 toward the extended position shown in FIG. 3. The hydraulic cylinder assembly 26 thus passes through a dead-center position as the pivot pin 28 moves from one side of the line L" to the other side, and this is brought about by gravity actuation of the second boom member 18.

When it is desired to return the boom members to the folded position, the first boom member 15 is moved to a position similar to that shown in FIG. 2 but with somewhat less angle with respect to the vertical. The second boom member 18 is then lowered until it approaches the vertical position, at which time it is permitted to swing free in order to cause the pivot pin 28 to cross the line L. The power cylinder assembly 26 is then energized to bring the second boom member 18 into close proximity to the first boom member 15. After turning of the base 13 to position the boom members over the cab 29 of the truck 10, the boom member 15 is lowered, along with the boom member 18, to return the parts to the folded position shown in FIG. 1, with the boom members resting on the stationary support 30. In this folded position the swinging end 31 of the second boom member 18 lies between the base supports 21 and closely adjacent to the pivotal supports 17.

The second boom member 18 is preferably formed of extensible parts. Thus, as best shown in FIGS. Sand 6, the extending end 31 is mounted on a beam 32 telescopically mounted within a coaxial beam 33 and held in position by means of a releasable transverse pin 34. The beam 33 rests on laterally-spaced support rollers 35 and its rearward end is carried on rollers 36 contacting'the underside of the box beam structure comprising a part of the second boom member 18. A series of holes, not shown, may be provided in the inner beam 32 for reception of the retainer pin 34. Power means are provided for extending the beam 33 with respect to the second boom member 18, and as shown in the drawings, this means includes a hydraulic power cylinder assembly 37 having one end secured at 38 to the beam 33 and having the other end secured at 39 to the second boom member 18. The second boom member 18 may be operated with the extending end 31 in retraced position with both beams 32 and 33 fully telescoped, or either or both of the latter may be extended, as shown by the phantom lines at the upper right-hand corner of FIG. 3.

The work-engaging element or weighted hook 41 is suspended from the cable 42 which passes over sheaves 43 and 44 and which is guided by the third sheave 45. The cable 42 also passes over the sheave 46 mounted near the swinging end of the first boom member 15, and the cable is wound on a power-operated drum 47 mounted on the base 13.

With both beams 32 and 33 fully extended, the crane is capable of unusually long reach in either horizontal or inclined position. Indeed, one of the advantages of the folding crane, as compared to a crane having a single telescopic boom, is that the base of the folding crane may be located closely adjacent a building, with the first boom member providing most if not all of the vertical reach, and the second boom member 18, with or without its extensions, providing most of the horizontal reach. When the second boom member extends upwardly at an angle, the total lift capacity of the folding crane may be considerably greater than the lift capacity of the single boom telescoping crane, for the same rated capacity.

In the copending application of Don Suverkrop, Ser. NO. 66,969, filed Aug. 26, 1970, there is disclosed a level-luffing crane vhaving first and second boom members pivotally connected for conjoint movement, and operated by hydraulic cylinder assemblies. When it is desired to move a load toward and away from the crane in a horizontal direction, the hydraulic cylinder assemblies are connected so that both booms move in' a manner to keep the load substantially at the same height. The hydraulic cylinder assemblies 22 and 26 of the present invention may be connected in such a manner as pointed outin said copending application Ser. No. 66,969, in order to achieve the same level-lufi'mg effect. The effect is shown by the phantom lines at the left-hand side of FIG. 3, where the boom members 15 and 18 are pivoted to different positions while maintaining the weighted hook 41 at substantially the same height.

In the modified form of the invention shown in FIG. 7, the hydraulic cylinder assembly 26a is employed instead of the hydraulic cylinder assembly 26. This assembly 264 includes a cylinder 61 slidably receiving two pistons 62 and 63 mounted on opposite sides of a stationary barrier wall 64 fixed within the cylinder 61. A piston rod 65 fixed to the piston 63 projects from one end of the cylinder 61 and is pivotally connected at 28 to the boom 18. Similarly, piston rod 66 is fixed to piston 62 and extends through the other end of the cylinder 61 and is pivotally connected at 27 to the boom 16. A chamber 67 defined between the piston 62 and the fixed barrier wall 64 receives hydraulic fluid through pipe 68. Similarly, chamber 69 defined between piston 63 and the stationary barrier wall 64 receives hydraulic fluid through the pipe 70. The cylinder 61 floats on the piston rods 65 and 66.

With the power cylinder assembly 26a in place, instead of the assembly 26, the booms 16 and 18 are raised while latched together until the boom 16 reaches the position shown in FIG. 2. The chamber 67 is allowed to collapse by permitting hydraulic fluid to escape through pipe 68, thereby permitting the boom 18 to fall free by gravity to the upright position shown in FIG. 2. During this movement, the pivotal connection 28 moves from the left side of the line L" to the right side thereof, across the dead center position. Hydraulic pressure is then applied through pipe 68 to expand chamber 67 to its maximum length. The hydraulic fluid in chamber 67 is then locked in. Swinging action of the boom 18 throughout its range of movement with respect to the boom 16 is then obtained by varying the amount of hydraulic fluid in the chamber 69 through the pipe 70.

It should be noted that, when the boom 16 is in the phantom line position shown in FIG. 3, the boom 18 is prevented from reaching folding position with respect to the boom 16 because the locked in hydraulic fluid in chamber 67 determines the minimum overall length of the hydraulic cylinder assembly 260, even through all of the hydraulic fluid in chamber 69 be withdrawn. This is a safety feature preventing the boom 18 from falling so low as to endanger the crane operator.

To fold the booms, the boom 16 is first placed in a position about midway between the vertical and the position shown in FIG. 2. Hydraulic fluid is removed from the chamber 69 to allow the boom 18 to descend by gravity. The chamber 69 is fully emptied and then hydraulic fluid is withdrawn from the chamber 67, thereby allowing gravity to move the pivotal connection 28 from the right side to the left side of the line L. The chamber 67 is again pressurized to latch the boom 18 under the boom 16.

In other respects, the folding crane employing the modified hydraulic cylinder assembly 26a shown in FIG. 7 operates in the manner previously described.

Having fully described my invention, it is to be understood that I am not to be limited to the details herein set forth but that my invention is of the full scope of the appended claims.

I claim:

1. In a folding crane, the combination of: a base, a pair of laterally spaced boom elements connected to form a first boom member, support means pivotally supporting said boom member on the base for movement in a vertical plane, hydraulic power means for swinging said first boom member with respect to the base to a vertical position and to both sides thereof, a second boom member having a pivotal connection, at a first pivot, with the first boom member for movement in the same plane, power means including an hydraulic power cylinder assembly for swinging the second boom member with respect to the first boom member between a folded position and an extended position, said hydraulic power cylinder assembly having a portion thereof positioned in the space between said boom elements and pivotally connected thereto at a second pivot and to a portion of said second boom member at a third pivot, said second boom member, when in folded position, having said portion thereof extending into the space between said boom elements and having its swinging end positioned adjacent said support means, the second boom member being movable by gravity toward and away from folded position by changing the inclination of the first boom member, in order to cause said third pivot to move across a line joining said first and second pivot to move said hydraulic power assembly through a dead-center position to enable said power assembly to lock said second boom in folded position.

2. In a folding crane, the combination of: a base, a first boom member pivotally mounted on the base for movement in a vertical plane, hydraulic power means for swinging the first boom member with respect to the base to a vertical position and to both sides thereof, a second boom member having a pivotal connection with the first boom member, at a first pivot, for movement in the same plane, second power means comprising a hydraulic cylinder assembly for swinging the second boom member with respect to the first boom member, said hydraulic cylinder assembly including two pistons slidably mounted within a cylinder on opposite sides of an internal barrier wall within the cylinder, each piston having a piston rod, the piston rods projecting through opposite ends of the cylinder, the cylinder floating on said piston rods, second pivot means connecting the first boom member to one of the piston rods, third pivot means connecting the second boom member to the other piston rod, said second boom being so swingable relative to said first boom that said third pivot means may pass to a position on either side of a line connecting said first and second pivot means.

3. The combination set forth in claim 2 in which a first pipe communicates with a first chamber defined within the cylinder and between one piston and said 7 barrier wall for selectively limiting the overall length of the first chamber is hydraulically pressurized.

UNITED STATES PATENT owner CERTWQATE or coR'EtTmN August 28, 1973 Patent No. 3 I 754 r 666 Dated Inventofls) Don Suverkrop It is certified that error appears in the above-identified patent and that said' Letters Patent are hereby corrected as shown below:

Title Page, column 1, Item [63] ind line should read "1970, now abandoned."

Specification, column 1, line 4 should read "now abandoned."

Signed and sealed this 1st day of Oetober 1974.

(SEAL) Attest:

McCOY M. GIBSON JR.' CO MARSI-LXLL DANN Attesting Officer Commissioner of Patents USCOMM-DC 60376-P69 1* us. GOVERNMENT Pmu'nuc orncs was 0-365-334 F ORM PO-1050 (-10-69) 

1. In a folding crane, the combination of: a base, a pair of laterally spaced boom elements connected to form a first boom member, support means pivotally supporting said boom member on the base for movement in a vertical plane, hydraulic power means for swinging said first boom member with respect to the base to a vertical position and to both sides thereof, a second boom member having a pivotal connection, at a first pivot, with the first boom member for movement in the same plane, power means including an hydraulic power cylinder assembly for swinging the second boom member with respect to the first boom member between a folded position and an extended position, said hydraulic power cylinder assembly having a portion thereof positioned in the space between said boom elements and pivotally connected thereto at a second pivot and to a portion of said second boom member at a third pivot, said second boom member, when in folded position, having said portion thereof extending into the space between said boom elements and having its swinging end positioned adjacent said support means, the second boom member being movable by gravity toward and away from folded position by changing the inclination of the first boom member, in order to cause said third pivot to move across a line joining said first and second pivot to move said hydraulic power assembly through a dead-center positIon to enable said power assembly to lock said second boom in folded position.
 2. In a folding crane, the combination of: a base, a first boom member pivotally mounted on the base for movement in a vertical plane, hydraulic power means for swinging the first boom member with respect to the base to a vertical position and to both sides thereof, a second boom member having a pivotal connection with the first boom member, at a first pivot, for movement in the same plane, second power means comprising a hydraulic cylinder assembly for swinging the second boom member with respect to the first boom member, said hydraulic cylinder assembly including two pistons slidably mounted within a cylinder on opposite sides of an internal barrier wall within the cylinder, each piston having a piston rod, the piston rods projecting through opposite ends of the cylinder, the cylinder floating on said piston rods, second pivot means connecting the first boom member to one of the piston rods, third pivot means connecting the second boom member to the other piston rod, said second boom being so swingable relative to said first boom that said third pivot means may pass to a position on either side of a line connecting said first and second pivot means.
 3. The combination set forth in claim 2 in which a first pipe communicates with a first chamber defined within the cylinder and between one piston and said barrier wall for selectively limiting the overall length of said second power means, and wherein a second pipe communicates with a second chamber defined within the cylinder and between the other piston and said barrier wall for swinging the second boom member when the first chamber is hydraulically pressurized. 